Hypoxia in the mountains - rules for climbing. Mountain sickness. Treatment and prevention. Providing assistance with mountain sickness

Altitude classification and characteristic physiological changes

Intermediate heights(1500-2500 m):
Physiological changes are noticeable. Blood oxygen saturation (saturation) > 90% (normal). The risk of altitude sickness is low.
High altitudes(2500-3500 m):
Mountain sickness develops during rapid ascent.
Very high altitudes (3500-5800):
Mountain sickness develops frequently. Saturation (saturation) of blood with oxygen Extreme Heights(>5800 m):
Severe hypoxemia at rest. Progressive deterioration despite maximum acclimatization. Constant stay at such altitudes is impossible.
The altitude at which mountain sickness develops varies due to the influence of numerous factors, both individual and climatic.
The following individual factors influence the development of mountain sickness.
individual resistance of people to lack of oxygen (for example, among mountain residents);
gender (women tolerate hypoxia better);
age (young people do not tolerate hypoxia well);
physical, mental and moral state;
level of training;
speed of climb;
degree and duration of oxygen starvation;
intensity of muscle effort;
past “high-altitude” experience.
The following factors provoke the development of mountain sickness and reduce tolerance to high altitudes:
presence of alcohol or caffeine in the blood;
insomnia, overwork;
psycho-emotional stress;
hypothermia;
poor quality and irrational nutrition;
violation of the water-salt regime, dehydration;
excess body weight;
respiratory and other chronic diseases (for example, tonsillitis, bronchitis, pneumonia, chronic purulent dental diseases);
blood loss.
The following climatic factors contribute to the development and faster progression of mountain sickness
Low temperatures - with increasing altitude, the average annual air temperature gradually decreases by 0.5 °C for every 100 m (in winter 0.4 °C, in summer 0.6 °C). In winter, at equal altitudes, the incidence is more frequent than in summer (for reasons, see pathogenesis). Sudden temperature changes also have an adverse effect.
Humidity - at high altitudes, due to low temperatures, the partial pressure of water vapor is low. At an altitude of 2000 m, air humidity is half that at sea level, and at high mountain altitudes the air becomes almost dry. On the one hand, this leads to increased loss of fluid by the body through the skin and lungs and, consequently, to dehydration of the body. On the other hand, more humid air has a higher thermal conductivity, therefore, contributes to the harmful effects of low temperatures. Thus, manifestations of altitude sickness in the mountains of a humid climate occur at a lower altitude (Alps - 2500 m, Caucasus - 3000 m) than in the mountains of a dry climate (Tian Shan - 3500 m, Himalayas - 4500 m).
Wind - high in the mountains, the wind can reach hurricane force (over 200 km/h), which overcools the body, exhausts us physically and mentally, and makes breathing difficult.
Altitude of development of mountain sickness
The combination of the above factors leads to the fact that the altitude of development of mountain sickness for different people and different conditions can be quite variable. Some begin to suffer from oxygen deficiency already at an altitude of 2000 m, while others do not feel its effect even at 4000 m.
Most healthy, non-acclimatized inhabitants of the plains begin to feel the effects of altitude in the region of 2500-3000 m, and with intense physical work, even at lower altitudes. At an altitude of about 4000 m, even absolutely healthy people experience slight malaise, and acute mountain sickness is registered in 15-20% of climbers. At an altitude of 6500-7000 m, complete acclimatization is apparently impossible at all, and therefore participants in expeditions to eight-thousanders around the world note numerous functional disorders and progressive signs of mountain sickness. In high altitude mountaineering there is a term "lethal zone" or "death zone".
Digestive system
At altitude, appetite changes significantly, the absorption of water and nutrients, and the secretion of gastric juice decreases, which leads to disruption of the processes of digestion and absorption of food, especially fats. As a result, a person sharply loses weight (up to 15-22 kg in 6-7 weeks at an altitude of 6000 m). At altitude, a person may feel an imaginary feeling of fullness in the stomach, distension in the epigastric region, nausea, and diarrhea that cannot be treated with medication.
Vision
At altitudes of about 4500 m, normal visual acuity is possible only at a brightness 2.5 times greater than normal for flat conditions. At these altitudes, there is a narrowing of the peripheral field of vision and a noticeable “fogging” of vision as a whole. At high altitudes, the accuracy of gaze fixation and the correctness of determining distance also decreases. Even in mid-altitude conditions, vision weakens at night, and the period of adaptation to darkness lengthens.
Dehydration
The excretion of water from the body, as is known, is carried out mainly by the kidneys (1.5 liters of water per day), skin (1 liter), lungs (about 0.4 liters) and intestines (0.2-0.3 liters), a total of about 3 liters of water per day. With increased muscle activity, especially in hot conditions, the release of water through the skin increases sharply (sometimes up to 4-5 liters). Intense muscular work performed in high altitude conditions, due to a lack of oxygen and dry air, sharply increases pulmonary ventilation and thereby also increases the amount of water released through the lungs. All this leads to the fact that the total loss of water among participants in difficult high-altitude trips can reach 7-10 liters per day.
Other changes
As hypoxia increases, pain sensitivity decreases until it is completely lost.

Altitude sickness clinic

The acute form of mountain sickness occurs when non-acclimatized people move quickly (within several hours) to high altitudes, usually to an altitude of more than 3500 m. Its clinical symptoms develop rapidly. In the subacute form of mountain sickness, they do not develop as quickly and last longer (up to 10 days). The clinical manifestations of both forms of mountain sickness are generally the same.

Acute mountain sickness

Easy degree
Symptoms of mild mountain sickness appear within 6-12 hours (and sometimes earlier) after ascending to a new altitude. At higher altitudes, its symptoms are detected earlier. For many, they initially manifest themselves in a deterioration in well-being and some lethargy. At first, a beginner feels unwell in the mountains, a rapid heartbeat, slight dizziness, slight shortness of breath during physical exertion, drowsiness, and at the same time has trouble falling asleep. After 3-4 days, these phenomena, if you do not rise higher, usually disappear. There are no clear objective clinical and neurological symptoms of this form of mountain sickness.
All of the above symptoms are not specific and can be the result of many other diseases. Nevertheless, it is considered correct to assume acute mountain sickness if a non-acclimatized person who has risen to an altitude of more than 2500 m begins to have a headache and at least one of the above symptoms appears. If the above symptoms appear after 36 hours of good condition, then the presence of another disease must be excluded.
Average degree
At altitudes of 2500-3500 m, some people may experience signs of euphoria: high spirits, excessive gesticulation and talkativeness, accelerated speech rate, causeless fun and laughter, a carefree, frivolous attitude towards the environment. Subsequently, the euphoric state is replaced by a decline in mood, apathy, melancholicity, and interest in the environment becomes dull.
At altitudes of 4000-5000 m, your health worsens. Moderate and even severe headache develops. Sleep becomes restless, anxious, with unpleasant dreams; some people have difficulty falling asleep and often wake up from a feeling of suffocation (periodic breathing). With physical effort, breathing and heart rate immediately increase, and dizziness appears. Appetite decreases, nausea occurs, which can be intense and can turn into vomiting. The taste changes: you want mainly sour, spicy or salty foods (which is partly explained by dehydration and a violation of the water-salt balance). Dry throat causes thirst. Possible nosebleeds.
Severe degree
At altitudes of 5000-7000 m and above, health is rarely good, more often it is unsatisfactory. There is a general feeling of weakness, fatigue, and heaviness throughout the body. Moderate and sometimes severe pain in the temples, frontal, and occipital parts of the head does not stop. Dizziness occurs with sudden movements and bends or after work. A person falls asleep with great difficulty, often wakes up, and some suffer from insomnia. A person suffering from altitude sickness is unable to perform physical activity for a long time due to shortness of breath (“breathing of a cornered dog”) and palpitations; work capacity drops, for example, at an altitude of 8000 m, 15-16% of work capacity remains from that produced at sea level.
The dryness in my throat is increasing, I feel thirsty all the time. The tongue is coated. Many people are bothered by a dry cough. Appetite is usually reduced or absent. The incidence of nausea and vomiting when eating food increases. Pain in the abdomen and gastrointestinal disorders, bloating are often observed. The breathing rhythm during night sleep is disrupted (Cheyne-Stokes breathing). The skin of the face, especially the lips, acquires a pale, often bluish, tint as a result of insufficient oxygen saturation of arterial blood, which loses its scarlet color. The temperature rises by 1-2°C, chills occur. Cases of bleeding from the nose, mouth, lungs (hemoptysis), and sometimes stomach bleeding are becoming more frequent.
Under certain conditions, starting from 4000 m, dangerous forms of mountain sickness may occur, caused by a breakdown of adaptation mechanisms and the development of more serious pathologies: pulmonary edema and cerebral edema.

High altitude pulmonary edema

Against the background of severe forms of acute mountain sickness, and sometimes suddenly, congestion of blood in the pulmonary circulation and pulmonary edema, as well as acute heart failure, may develop.
Symptoms of high-altitude pulmonary edema usually appear within 2-3 days of staying at high altitude. Liquid emerges from the capillaries of the lungs, which, entering the lumen of the alveoli, interferes with gas exchange, as a result, hypoxia intensifies and the disease progresses. If left untreated, it can take a matter of hours from the first onset of symptoms to death from suffocation. Its development is facilitated by previous diseases of the respiratory and circulatory system, chronic or acute respiratory tract infection (for example, tonsillitis, bronchitis, pneumonia, chronic purulent dental diseases), excessive physical activity performed before stable adaptation has occurred.
High altitude pulmonary edema of all mountain-specific diseases is the most a common cause of death. At 2700 m the incidence of high altitude pulmonary edema is 0.0001% and increases to 2% at 4000 m.
There are 3 stages in the development of high-altitude pulmonary edema:
First stage
Occurs against the background of symptoms of severe acute mountain sickness:
the patient stands on his feet, but does not move independently;
absence of urine for more than 8-10 hours;
symptoms of depression of the respiratory center are observed - rapid pulse and breathing, difficulty coughing, the wings of the nose first participate in breathing, teeth are clenched;
chills, fever;
skin is moist, pale;
cyanosis: blue nails, lips, nose, ears.
The following specific symptoms are also characteristic of pulmonary edema:
dry cough, sore throat;
complaints of compression below the sternum, chest pain;
symptom of “vanka-stand up”: due to weakness, the patient tries to lie down, but due to suffocation he is forced to sit down;
Temperature 38-39°C. If pulmonary edema develops without pneumonia, the temperature can be 36-37°C.
Second stage
Usually, 8-12 hours after the first symptoms, the second stage of pulmonary edema occurs:
the patient can no longer stand;
cough with foamy sputum;
the pulse is rapid, blood pressure constantly rises;
breathing is noisy, wheezing is heard when listening;
symptom of “vanka-stand up” or semi-sitting position;
thirst.
Third stage
Develops after another 6-8 hours and 4-8 hours before death:
signs of significant dehydration: increased thirst;
severe headache;
temperature increase;
motor restlessness;
wheezing heard at a distance;
bloody sputum, pink foam from the nose and mouth;
suffocation;
arrhythmia, pressure can reach 150-170/90-100.
Without proper treatment, a drop in pressure, collapse, coma, and cardiac arrest occurs.

High altitude cerebral edema

High-altitude cerebral edema can be considered an extreme manifestation of acute mountain sickness. Fluid comes out of the capillaries of the brain, and it increases in volume. In this case, the cerebellar tissue is wedged into the spinal cord trunk, the vital centers located in it are destroyed, and death occurs.

Prevention of altitude sickness

1. 3 months before the ascent, start jogging (treadmill, shaping, fitness, cardio equipment) 3 once a week, no less than 30-40 minutes, to prepare the heart, blood vessels and respiratory system.
2. 2 months before the ascent, take medications, increasing hemoglobin blood, adaptogens and capillary protectors(capilar tablets, 3-4 pcs. on an empty stomach, chew)
3. Those who are weather-sensitive, prone to headaches, and people with cervical osteochondrosis should take Cavinton or Ginko Biloba a month before the ascent to improve cerebral circulation.
4. Take multivitamins a month before climbing the mountains (with the obligatory content of all microelements) and continue taking daily multivitamins in the mountains(you can use vitamin complexes for athletes or pregnant women, with a high content of minerals).
5. It is recommended to take acetylsalicylic acid daily in the mountains (aspirin, ACC thrombosis) to thin the blood and improve oxygen transport, and additional intake vitamin C(it is better to take a soluble form of 500 or 1000 mg).
6. Have all the following medications in your personal first aid kit: Acetazolamide (Diacarb, Diamox), Dexamethasone (including the ampoule form of the drug) asparkam or panangin(they are taken together with diacarb), ibuprofen or solpadeine(good for relieving headaches during the initial symptoms of mountain sickness). Anti-cold medications, immunomodulators (oscillococcinum, anaferon) should be taken immediately in case of hypothermia, chills, runny nose, or if any adenoviral infections occur in the group. Sputum thinners (for example, ACC, which should be taken in case of any form of cough, for early prevention of pulmonary edema), cerucal (antiemetic).
Three golden rules for preventing altitude sickness:
1. Never climb with symptoms of altitude sickness.
2. If the symptoms of mountain sickness intensify, then you definitely need to descend.
3. If a climber feels unwell at altitude, then in the absence of obvious signs of other diseases, it is necessary to assume that he has acute mountain sickness and carry out appropriate treatment.
The basis for the prevention of acute mountain sickness is active step-by-step acclimatization. Rational selection of people, their physical and psychological preparation, previous high-altitude experience, and pharmacological prevention are also of no small importance.

Acclimatization

Basic principles of acclimatization:
Up to an altitude of 3000 m, increase the overnight altitude by 300-600 m every day.
When climbing more than 3000 m, take a day's rest every 1000 m.
Keep in mind that the rate of acclimatization varies significantly among different people.
If possible, do not travel by transport (airplane or car) immediately to high altitudes.
When delivering by transport to a high altitude, do not rise even higher during the first 24 hours.
"Climb high, sleep low."
The main acclimatization occurs in the first three days of travel.
If symptoms of altitude sickness persist, climbing should be suspended.
If symptoms increase, you should begin descent as quickly as possible.

Pharmacological prevention

To prevent acute mountain sickness, the same medications are usually used as for treatment. When ascending to an altitude of more than 3000 m, the following drugs can be recommended (recommended daily doses are indicated in parentheses):
Acetazolamide (diacarb, diamox) is a diuretic drug that also reduces the production of cerebrospinal fluid in the intracranial space, which reduces intracranial pressure and can reduce or eliminate the symptoms that occur with mountain sickness; the prophylactic prescription of the drug is poorly justified. The presence of bursting headaches that intensify when bending over, a feeling of pressure on the eyeballs from inside the skull, nausea, especially vomiting indicate an increase in intracranial pressure and in most cases are an indication for taking Diacarb. Dosages are individual and for a person not taking Diacarb it can range from 1/4 to 1 tablet. Side effects of acetazolamide include paresthesia (pins and needles) and increased diuresis (urination). If paresthesia and convulsions occur, you can take potassium supplements: Panangin up to 6 tablets/day. Typically, the prescription of diacarb involves the simultaneous use of drugs containing potassium and magnesium salts (asparkam, panangin, 1-2 tablets 2-3 times a day, depending on the amount of physical activity, since a significant amount of this salt is also released with sweat), the occurrence of the above symptoms, and Also, intestinal bloating, which may be caused by a low concentration of potassium salts in the blood and tissues of the body, is an indication for mandatory intake of potassium salts in double dosages compared to preventive ones. Also required increase the volume of fluid consumed to avoid dehydration and, as a result, blood thickening and deterioration of its fluidity. Acetazolamide is a sulfonamide diuretic and should not be used by persons allergic to this group of drugs. The changes in the body caused by the drug are very significant and taking Diacarb without serious indications is t.c. for preventive purposes, a gross mistake.
Dexamethasone - (4 mg every 6 hours) reduces the severity and severity of acute mountain sickness during a sharp rise to altitudes above 4000 m. Prophylactic administration can be started several hours before the ascent. Dexamethasone is not the first choice drug for the prevention of altitude sickness due to its side effects. Its use is justified only in persons intolerant to acetazolamide, predisposed to developing altitude sickness and if a rapid climb to altitude is planned. Dexamethasone relieves symptoms of acute mountain sickness for several hours, but does not promote acclimatization.
Dibazol is a vasodilator with adaptogenic properties. (0.5 tablets of 10 mg).
Viagra - several years ago, research began on the use of Viagra as a prophylactic agent. Viagra improves peripheral blood circulation, including in the lung area.
Vitamins, microelements and amino acids:
Ascorbic acid (vitamin C) - having antioxidant properties, reduces the accumulation of under-oxidized metabolic products that appear during hypoxia. The daily requirement under normal conditions is 70-100 mg, and during acclimatization it is advisable to increase the dose several times (up to 500 mg 2 times a day).
Tocopherol (vitamin E) (200 mg 2 times a day) and lipoic acid (300 mg 2 times a day) also have antioxidant properties.
Calcium pangamate - has a distinct antihypoxic effect (2 tablets of 50 mg each).
Calcium pantothenate - (vitamin B3), normalizes metabolic processes (1 tablet of 100 mg)
Potassium orotate - normalizes the functioning of the liver and heart, microcirculation in the capillaries (1 table)
Glutamic acid is an amino acid, a participant in metabolic processes (2 tables).
Methionine is an amino acid that normalizes liver function during hypoxia and the absorption of fats (3 tables).
Panangin (asparkam) is a potassium-magnesium salt of the aspartic amino acid, antiarrhythmic, conducts K+, Mg2+ ions into cells (1-2 tables).
Riboxin - enhances the effect of potassium orotate, has a beneficial effect on the heart and liver (Table 1-2).
Of the nutrients, carbohydrates significantly increase resistance to hypoxia, so at altitude, to prevent mountain sickness, you need to use more glucose, sugar and other easily digestible carbohydrates, but not more than 300-400 g per day. For drinks, we can recommend canned orange juice, a warm solution of lemon juice powder, and chamomile tea. At altitude, you should not drink excessively strong tea. It excites the nervous system, and thereby contributes to the development of insomnia.
Coca in the form of tea and chewing leaves, contrary to popular belief, contains very little cocaine, and in moderation promotes acclimatization. Therefore, while in the Andes, do not neglect the advice of guides who suggest its use.
Ginkgo Biloba extract (bilobil), tablets, capsules 40 mg (80-120 mg 2 times a day).
Analgesics from the group of non-steroidal anti-inflammatory drugs - aspirin, ibuprofen, paracetamol, etc.: (400-600 mg, if necessary, the dose can be repeated, but not more than 1.2 g of ibuprofen, 3 g of aspirin or 4 g of paracetamol per day).
Alcohol at an altitude of more than 3000 m, even in small doses, reduces the respiratory rate and increases hypoxia, so the consumption of alcoholic beverages in the high mountain zone should be prohibited.

Treatment of acute mountain sickness

Light and medium degree

It must be emphasized that a mild degree of mountain sickness, despite the unpleasant sensations, is usually only a condition that physically limits a person without any lasting consequences. Basics of treating mild symptoms of mountain sickness:
Rest;
Liquids (juices, teas);
Weak analgesics (aspirin, ibuprofen, paracetamol);
medicines for nausea and vomiting (aeron, sour fruits - apples, oranges, lemons, apricots
If necessary, appoint acetazolamide 125-250 mg twice daily for 3 days.
Under favorable circumstances, symptoms usually disappear after 2-4 days.
Severe degree
The most effective method of treatment is to lower the victim down. Every opportunity for independent movement of the victim should be fully used, which does not allow apathy, indifference and hypothermia to develop.
In extreme cases, you should use an oxygen mask (preferably with carbon gas: O2 + 5-7% CO2). It is effective to use a portable hyperbaric chamber (compression chamber), which is a sealed bag into which air is pumped with a hand pump.
Acetazolamide 125-250 mg twice daily for 3 days.
Dexamethasone 8 mg orally, then 4 mg every 6 hours during the day.
The temperature should be reduced to 37 °C with antipyretic drugs.

Treatment of pulmonary edema

The most important method of combating pulmonary edema is immediate descent. Descending even a few hundred meters can lead to improvement.
The use of a portable hyperbaric chamber is effective. In extreme cases, an oxygen mask should be used.
The victim must be placed in a semi-sitting position.
If the upper pressure (systole) is more than 90 mm Hg. Art., then 2-3 ampoules of furosemide must be administered intramuscularly.
Nifedipine is effective for the prevention and treatment of high-altitude pulmonary edema (initially 10 mg orally, then 20 mg of slow-release nifedipine every 12 hours).
Place a nitroglycerin tablet under the tongue (if the upper pressure (systole) is more than 90 mm Hg). Nitroglycerin can be given again after 20 minutes no more than 3 times.
Apply venous tourniquets to the thighs so that the pulse of the arteries can be felt below the place where they are applied. This will create a blood depot in the lower extremities and prevent it from returning to the heart.
Important: you need to know that no medicinal manipulations should serve as a delay for going down.
Pulmonary edema can develop very quickly against the background of inflammatory diseases of the respiratory tract (sore throat, pneumonia), therefore when signs of these appear, the person must be taken down, while providing symptomatic drug assistance.

Treatment of cerebral edema

If symptoms of high-altitude cerebral edema appear, you should immediately begin descent. A delay can lead to the death of the patient. If symptoms appear in the evening, you cannot wait until the morning to come down. It is necessary to evacuate at least to the altitude at which the person last felt well, and preferably up to 2500 m. As a rule, if descent is started in time, the symptoms quickly and completely disappear.
We need to start supplying oxygen.
Dexamethasone intramuscularly (be sure to have ampoules and syringes with you).
Medicines for cerebral edema play a rather auxiliary role, but, nevertheless, they should not be neglected. To reduce symptoms and facilitate evacuation, dexamethasone is used (initially 8 mg, then 4 mg every 6 hours orally or parenterally).
Should not be used for cerebral edema both vasodilators (nitroglycerin, nifedipine, trental) and blood pressure-increasing drugs (caffeine, adrenaline): any increase in pressure or vasodilation will increase cerebral edema. The use of diuretics is now also not recommended.
The disappearance of symptoms does not occur immediately after descent, and the patient should be transferred under the supervision of medical workers.

At an altitude of several kilometers, a person begins to feel a lack of oxygen in the blood - he develops altitude or mountain sickness. Experienced climbers warn – this is no joke! Oxygen starvation can lead to irreversible health consequences, so when going to the mountains, do not forget about the first aid kit and safety equipment. Interestingly, this illness can be detected not only by poor health, but also by changes in behavior. But first things first.

What is altitude sickness

Among themselves, climbers call altitude sickness by affectionate nicknames: mountain climber or acclimator. However, a diminutive name in slang does not make the disease less dangerous. Altitude sickness is hypoxia (oxygen starvation of body tissues) when raised to a height of 2.5 thousand meters. This problem is also manifested by a lack of carbon dioxide (hypocapnia) and other changes in human organs. When planning to conquer the next peak, take a professional high-altitude climber and a medical worker into your group. These people can save your life.

At what altitude does oxygen starvation begin?

High blood pressure at an altitude of 3000 meters is the first symptom of altitude sickness, according to statistics, which can occur earlier - from 2000 meters above sea level, here everything depends on individual conditions (the physical form of the climber, chronic diseases, ascent speed, weather conditions and other factors) . The first signs can be felt at an altitude of 1500 meters; above 2500 meters oxygen starvation manifests itself in full force.

Symptoms

Let's look at the symptoms of oxygen starvation when climbing to altitude. Depending on the number of meters traveled, the symptoms of altitude sickness intensify. At first, a person attributes everything to fatigue, however, the higher you go, the more difficult it is to ignore the symptoms of altitude sickness. At an altitude of 1500 meters, the pulse quickens and there is a slight increase in blood pressure. At the same time, the level of oxygen in the blood remains within acceptable limits.

Above 2500 meters, the symptoms begin to quickly “gain momentum”, especially when it comes to high-speed acclimatization. If the ascent to the mountains is carried out in a short time of up to 4 days, then climbers talk about a technically difficult route. At this stage, participants experience problems with the nervous system. A person may experience irritation and increased aggression towards other participants.

If there is a change in behavior, it is recommended to check the cardiovascular system. The pulse will be increased to 180 beats per minute or more. The heart works intensively, trying to supply the body with the necessary amount of oxygen. At this altitude, breathing problems will begin. The number of breaths during acclimatization in one minute will exceed 30 times. The presence of such symptoms indicates a diagnosis of altitude sickness.

Signs

At an altitude of more than 3500 meters, the signs of oxygen starvation will intensify. Problems with sleep will begin: pathologically rare breathing caused by hypocapnia. At the same time, a lack of carbon dioxide will provoke a decrease in the number of breaths during sleep, and this leads to an increase in hypoxia. As a result, short-term suffocation and respiratory arrest may occur during sleep. Neurological disorders will increase, the climber will begin to see hallucinations and be in a state of euphoria.

Symptoms of altitude sickness may worsen with intense physical activity. However, small loads can be useful under hypoxic conditions. They enhance metabolic processes in the body, thereby reducing oxygen starvation. At an altitude of over 5800 meters, the body begins to suffer from a lack of water - dehydration, a deficiency of potassium, magnesium and other trace elements occurs. If we add to this climatic conditions, such as strong winds and sudden changes in temperature, then a long stay here is impossible for unprepared people.

If you climb 8 km into the mountains, it is dangerous to stay here for more than two days without acclimatization. This applies even to experienced trained climbers who have not lost their reserves along the way. The 8,000 meter mark is called the “death zone.” This means that energy consumption exceeds its intake into the body through food, air, and sleep. Without a reserve of strength, a person dies. Death from altitude in medicine was confirmed by the depressurization of the aircraft at an altitude of 10 km: without additional oxygen, passengers died.

Causes of altitude sickness

The cause of altitude sickness is a lack of oxygen and carbon dioxide, which is accompanied by difficult hiking conditions. The climber's breathing becomes faster and deeper. The heart undergoes increased stress during this period: it increases the number of blood cycles over a certain period of time. Result: increased heart rate. The liver, bone marrow and other organs begin releasing red blood cells, which leads to an increase in hemoglobin. Changes also occur in the muscles due to the load on the capillaries.

Lack of oxygen leads to poor brain function. Hence - clouding of consciousness, hallucinations, behavioral disturbances, etc. Hypoxia also affects the gastrointestinal tract. Climbers lose their appetite, suffer from vomiting and abdominal pain. Impaired liver function leads to fever. At a body temperature of 38 degrees, the body requires twice as much oxygen, which is already in short supply. In this case, the expedition member must be urgently evacuated down.

Stages

The development of altitude sickness and the mechanism of manifestation of symptoms are conventionally divided into stages. In many ways, this classification depends on the height of the climb, the physical training of the climber, the time spent at a particular height, the region and even the gender of the climber. For example, a height of 7 km in the Himalayas feels like 5 km on Elbrus. Interestingly, women tolerate hypoxia more easily. Conventionally, altitude climbers divide altitude sickness into the following stages:

• Stage 1. The first symptoms appear. This occurs at a low altitude of 2000-3000 meters. An upset stomach, mood swings, poor sleep, and shortness of breath appear. The climber loses his appetite. If at the end of the day there is a desire to eat all the reserves, it means that acclimatization is occurring. This is a good reaction to height.
• Stage 2. Height – 4-5.5 km. Altitude sickness manifests itself in a throbbing headache, severe nausea, and vomiting. There is forgetfulness, clouding of consciousness, loss of concentration, drowsiness, blurred vision, loss of fluid in the body.
• Stage 3. Height – 5.5-6 km. The headache continues to be tormented, which is not suppressed even by potent analgesics. The vomiting does not stop, but a new symptom is added: cough. The climber loses orientation and coordination of movements.
• Stage 4. Altitude 6 km. Climbing can cause swelling of the brain and lungs. Urgent descent down!

Varieties

Altitude sickness can present with its own symptoms for every climber. Individual characteristics make themselves felt at different heights. This is especially true for altitudes above 5000 meters. Therefore, it is better not to cross this line without an experienced climber and medic. Please note that death from altitude sickness occurs very quickly, so getting caught up in the excitement can be life-threatening.

Treatment of altitude sickness

Inexperienced climbers, when faced with acclimatization at altitude, can develop pulmonary and cerebral edema, which is especially dangerous without proper medical care in mountainous areas. Remember that acute altitude sickness can only be cured by descending, and the following remedies will help relieve symptoms:

• Imodium or its analogues for intestinal disorders;
• Acetazolamide or Diacarb to lower blood pressure;
• analgesics for headaches;
• strong tea that relieves drowsiness.

Treatment of pulmonary edema

What to do if the worst thing happens - pulmonary edema? Urgently hospitalize the patient downstairs, otherwise death cannot be avoided. On the way, every half hour, give him a nitroglycerin tablet under his tongue and give him a Lasix injection. If you have a fever, you can use any drug that reduces the temperature. Give the drink one sip at a time, do not give salty food, keep the patient in an upright position.

Treatment of cerebral edema

You can avoid the consequences of cerebral edema only by starting an immediate, rapid descent. On the way, the patient needs to take two Diacarb tablets, then one tablet twice a day. You will need to give an injection of Dexamethasone (3 ml), injections of which must be repeated every 6 hours. For fever, any suitable remedy, for example, Paracetamol, will do. Do not give a lot to drink, do not put it in a horizontal position.

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What is mountain (altitude) sickness?

Mountain sickness is a special painful condition that occurs when climbing to high altitude areas with thin air. It can be observed in climbers, geologists when climbing mountains, when climbing mountains by vehicle, by cable car, etc., as well as in people arriving in high-mountainous areas to work before they have adapted to the altitude.

The painful condition that occurs under these conditions has been known to mankind for a very long time. The very name “mountain sickness” is usually attributed to Acosta (1590), who observed a sharp deterioration in health in himself and his companions upon reaching an altitude of 4500 m above sea level while traveling in the Peruvian Andes. But systematic study of the effect of altitude on the body began only in the second half of the 19th century.

It was then established that the main etiological factor of mountain sickness is a decrease in the partial pressure of oxygen in the inhaled air as one rises to altitude. Other unfavorable factors specific to high mountain areas and contributing to the development of altitude sickness are enormous physical activity when climbing mountains on foot (climbers), low humidity and air temperature, strong winds, and increased ultraviolet radiation.

Along with the advent of the first aircraft, and then more advanced aircraft that made it possible to quickly reach great heights, new factors arose that negatively affected the body. These are, first of all, sharp changes in atmospheric pressure, high accelerations, noise, increased levels of carbon monoxide, gasoline vapors and other toxic impurities in the air of closed cabins, as well as significant stress on the nervous system.

The pathological condition that occurs in pilots at altitude as a result of hypoxia is commonly called altitude sickness.

The creation of jet and turbojet aircraft flying at speeds exceeding the speed of sound at an altitude of more than 20 km could not but lead to new requirements for ensuring human safety in flight. In conditions of reliable sealing of the cabin, the creation of special suits and equipment that ensures a sufficient supply of oxygen to the crew, the effect of hypoxia on the body is small. The main factors that negatively affect a person in high-altitude flight are sudden decompression, large accelerations as a result of sudden changes in speed and direction of flight, shock loads, vibration, breathing under pressure, the toxic effect of harmful substances and significant psychomotor and emotional stress.

At the same time, the problem of hypoxia remains relevant for these flights, since emergency situations are always possible when oxygen-breathing equipment fails at high altitudes. The idea of ​​mountain sickness as a type of altitude sickness can also be preserved to denote a painful condition that occurs in a person during a rapid ascent to an altitude of over 3500-4000 m on an airplane, helicopter, balloon and other transport that does not provide reliable sealing of the cabins and oxygen breathing with the help of special equipment.

Causes of air sickness

In its pathogenesis and clinical manifestation, mountain sickness is similar, but not identical to altitude sickness due to the fact that the effect of hypoxia in it is usually longer lasting. In addition, when climbing to a height, the pilot goes from normal atmospheric pressure to reduced pressure within a short period of time and, along with the cold, feels the influence of vibration, noise, acceleration and pressure changes in the rarefied atmosphere.

It is known that the properties of the atmosphere, the gas shell surrounding the earth, change with altitude. Currently, the atmosphere is usually divided into four main layers: the troposphere, stratosphere, ionosphere and exosphere. Altitude sickness occurs within the troposphere - the lower layer of the atmosphere in direct contact with the ground. The troposphere has different heights depending on the latitude of the area and the time of year. On average, the height of the troposphere is 9-11 km. Above the equator, the boundary between the troposphere and the stratosphere lies at an altitude of 16-18 km above sea level, at the north pole - 7-10 km, at the south pole - 5-6 km. In summer, the troposphere ceiling is 1.5 times higher than in winter.

Atmospheric air near the ground consists of a physical mixture of gases in certain proportions. Dry atmospheric air contains: nitrogen 78.08%, oxygen 20.93%, argon 0.94%, carbon dioxide 0.03%, hydrogen, neon, helium, etc. about 0.01%.

It is important to emphasize that in different regions of the globe and at different altitudes, the percentage of oxygen - the most important component of the atmosphere for living organisms - remains almost unchanged up to an altitude of 19,000 m. However, air density is a variable value. If at the sea surface at a pressure of 760 mm Hg and a temperature of 0° the density of dry air is 1293 g per 1 m3, then at an altitude of 5000 m it decreases by almost 50%.

The atmosphere produces pressure on the surface of the earth, which at sea level averages 1033 kg per 1 cm2, which is equivalent to the weight of a column of mercury with a base area of ​​1 cm2 and a height of 760 mm at 0°. With increasing altitude, atmospheric pressure decreases exponentially, and the faster the higher the temperature. Up to an altitude of 1000 m, for every 10.5 m, atmospheric pressure decreases on average by 1 mm Hg.

Since atmospheric air at sea level under standard conditions exerts a pressure equal to 760 mm Hg, and the oxygen content in the air is 20.93%, then the partial pressure of oxygen at sea level is 760 x 0.2093, i.e. 159 mm mercury column.

According to Dalton's law, the partial pressure of any gas in a mixture is equal to the pressure that this gas would produce if it alone occupied the entire volume of the mixture of gases. When rising to a height of up to 19,000 m, the partial pressure of air gases, including oxygen, decreases in proportion to the decrease in atmospheric pressure, since the percentage composition of air remains constant. At a pressure of 0.5 atmospheres, i.e. at an altitude of approximately 5400 m, the partial pressure of oxygen will already be equal to 79.5 mmHg (380 x 0.2093). Therefore, the greater the distance from the ground, the lower the partial pressure of oxygen.

It is known that gas exchange in the lungs occurs due to the difference in the partial pressure of oxygen and carbon dioxide in the alveolar air and in the blood. In the alveolar air at sea level, the partial pressure of oxygen is on average 103 mmHg, and that of carbon dioxide is 39-40 mmHg. In the blood flowing to the lungs, the partial pressure of oxygen is usually 30-50 mmHg, and that of carbon dioxide is approximately 40-65 mmHg.

According to the law of diffusion, gases move from a medium with a higher partial pressure to a medium with a lower pressure. In this case, oxygen passes from the pulmonary alveoli into the blood, and carbon dioxide, on the contrary, from the blood into the alveoli.

At normal atmospheric pressure of 760 mmHg in a healthy person, blood oxygen saturation in the lungs reaches 95-97%. Thus, for every 100 ml of blood there are 18.5 ml of chemically bound oxygen in the form of oxyhemoglobin and approximately 0.24 ml of oxygen is in the blood in a state of physical solution.

Directly in the tissues of the body between arterial blood and cells, the reverse process occurs. Oxygen from the blood diffuses into the cells, into an environment with a lower partial pressure, and carbon dioxide, on the contrary, from the tissue into the blood. At altitude, under conditions of lower partial pressure of oxygen in the atmosphere, and accordingly in the alveolar air, oxygen saturation of the blood decreases, which leads to tissue hypoxia with the subsequent development of a symptom complex called mountain sickness.

Classification of hypoxia

There are several classifications of hypoxia

One of the first to propose and become widespread was the Barcroft classification of hypoxia with the addition of Peters and van Slyke. According to this classification, four types of hypoxia are distinguished:

1) anoxic hypoxia (anoxemia), in which there is a low oxygen content in the arterial blood. This type of hypoxia occurs during ascent to altitude, when the partial pressure of oxygen in the atmosphere and alveolar air falls and normal saturation of blood hemoglobin with oxygen does not occur;

2) anemic hypoxia, in which the oxygen tension in the blood is normal, but there is not enough hemoglobin to bind the oxygen required for normal life;

3) stagnant hypoxia, when arterial blood contains a normal amount of oxygen, but due to stagnation, for example during cardiac decompensation, the delivery of oxygen to tissues per unit time is slowed down;

4) histotoxic anoxia (hypoxia), observed in poisoning and in all other cases when tissue cells lose the ability to utilize oxygen.

There is another classification:

1. Hypoxemic hypoxia:

a) from a decrease in the partial pressure of oxygen in the inhaled air; b) as a result of difficulty in the penetration of oxygen into the blood through the respiratory tract; c) due to respiratory distress.

2. Hemic hypoxia:

a) anemic type;

b) hypoxia during hemoglobin inactivation.

3. Circulatory type of hypoxia:

a) stagnant form;

b) ischemic form.

4. Tissue hypoxia.

The third, different classification aims to highlight the most common type of oxygen starvation, which combines some of the types of hypoxia given above:

1) oxygen starvation due to a decrease in the partial pressure of oxygen in the inhaled air;

2) oxygen starvation during pathological processes that disrupt the supply of oxygen to tissues at normal levels in the environment. These include the following types of oxygen starvation:

a) respiratory (pulmonary);

b) cardiovascular (circulatory);

c) blood;

d) fabric;

d) mixed.

Mountain sickness, which occurs when climbing to high altitudes, as well as during a long stay at relatively low altitudes (2000-3000 m), primarily due to a decrease in the partial pressure of oxygen in the inhaled air, is based on the development of hypoxemic hypoxia.

As mentioned above, at sea level the hemoglobin of arterial blood is 95-97% saturated with oxygen and, therefore, under these conditions the blood contains 18.5 vol.% oxygen (full, i.e. 100%, saturation would be equal to 20 vol. . %). When passing through the capillaries, about 5 vol. is removed from the blood. % oxygen, so mixed venous blood contains about 14 vol. % of it, in other words, her hemoglobin is only 70% saturated with oxygen.

Thus, during hypoxemic hypoxia, as a result of a decrease in the partial pressure of oxygen in the alveolar air and in the blood, the saturation of hemoglobin with oxygen decreases. Under these conditions, the supply of oxygen to the body's cells deteriorates, since the pressure gradient between capillaries and tissues also decreases. The rate of oxidative processes in tissues also changes, which depends on the magnitude of the partial pressure of oxygen in the blood. This factor in the pathogenesis of hypoxia during mountain sickness is currently given, perhaps, greater importance than the decrease in the oxygen capacity of arterial blood.

A decrease in the partial pressure of oxygen in the inhaled air when ascending to a height in the initial stage, with moderate degrees of hypoxia, causes a number of physiological protective and adaptive reactions on the part of the body. The resulting increased breathing leads to the leaching of carbon dioxide from the lungs, as a result of which its partial pressure in the arterial blood decreases.

If we consider that under normal conditions, a sufficient partial pressure of carbon dioxide in the blood is one of the important factors in the process of dissociation of oxyhemoglobin, then a decrease in this pressure makes it difficult for hemoglobin to release oxygen from the blood. Consequently, hyperventilation, which at first glance is an expedient compensatory reaction in response to a lack of oxygen in the inhaled air, in turn leads to excessive release of carbon dioxide by the lungs. It is known that, in addition to participating in the regulation of respiration and blood circulation, carbon dioxide is an important factor in maintaining acid-base balance. Therefore, during hypoxia, as a result of a violation of the acid-base balance, under-oxidized metabolic products accumulate in the blood.

Clinical picture and pathogenesis

Clinical manifestations of mountain sickness in the initial phase are caused mainly by acidosis, and later by alkalosis (autointoxication theory).

The pathogenesis of mountain sickness is quite complex.

Lack of oxygen at altitude (hypoxemic hypoxia) is accompanied by a number of changes in the ratio of blood gases like a “chain” reaction. As a result of this, firstly, the rate of oxidation in tissues decreases due to a decrease in the partial pressure of oxygen and a decrease in the oxygen capacity of arterial blood; secondly, increased and rapid breathing helps to wash out carbon dioxide from the lungs, reduce its partial pressure in the blood and leads to difficulty in dissociating oxyhemoglobin; thirdly, depletion of blood in carbon dioxide causes a shift in the acid-base balance towards alkalosis and the accumulation of under-oxidized metabolic products in the body.

Our country has many high mountainous regions where thousands of people live. Mountaineering has become widely developed. This dictates the need for even more persistent study of the state of the physiological systems of the body and its adaptive reactions when rising to altitude.

Currently, some new data have been obtained that shed light on other mechanisms involved in the occurrence and manifestation of mountain sickness. In particular, experimental studies have proven that dysfunction of individual organs and systems during oxygen starvation is of a reflex nature. Switching off the receptors of the sinocarotid zones in animals increases resistance to oxygen starvation.

Along with hypoxia, a number of factors in the internal and external environment of the body are of significant importance in the occurrence and development of the symptom complex of mountain sickness. Wind, dry mountain air, and the appearance of snow and ice in the mountains often contribute to an earlier onset of the disease. In different climatic conditions, mountain sickness occurs at different altitudes: in the Alps and the Caucasus - at an altitude of 3000 m, in the Andes -4000 m, and in the Himalayas - when climbing mountain ranges 5000 m high.

Along with this, the time of onset and severity of the clinical picture of mountain sickness are largely determined by age and health status. Pre-existing illnesses, poor nutrition, insufficient rest in the absence of acclimatization before ascending to altitude significantly reduce the body's stability. In these cases, the first manifestations of altitude sickness may develop already at an altitude of 2500-3000 m. Of course, the speed of ascent to altitude also matters.

Symptoms of altitude sickness

Symptoms of mountain sickness in different individuals can develop at different altitudes, depending on the individual characteristics of the body and its resistance to oxygen starvation, as well as the degree of fitness. Most people do not experience altitude sickness at altitudes of 2500-3000 m.

In older people, mild signs of altitude sickness in the form of drowsiness can occur already at an altitude of 1000 m. Starting from an altitude of 3000 m, especially during physical activity, most people experience the well-known symptoms of altitude sickness: shortness of breath, headache, etc., and with At altitudes of 4000 m, mountain sickness usually develops.

The painful condition can arise suddenly, in the midst of complete health, or develop gradually after barely noticeable precursors in the form of dizziness, increased fatigue and apathy. Subsequently, general weakness increases, a feeling of chilliness, a painful headache (mainly in the forehead) and vomiting appear. Sleep becomes restless, appetite disappears, disturbances in higher nervous activity increase, and cyanosis appears. In severe cases, these symptoms may be followed by loss of consciousness.

The sequence of occurrence of functional and then organic changes in various organs and systems depends not only on the duration of hypoxia, but also on the sensitivity of tissues to oxygen starvation.

Changes in the nervous system

The higher parts of the central nervous system are most sensitive to oxygen deficiency. Along with general weakness, increased fatigue, lethargy, insomnia or, conversely, drowsiness and apathy, mental disorders are observed in a person. One of the first signs of altitude sickness may be an uncritical assessment of your condition. As mountain sickness develops, even slight mental stress causes headaches. The amount of memory and attention decreases sharply: simple mathematical calculations become difficult. One can often observe peculiar changes in character. For some, these changes are expressed in weakness, lethargy, indifference, and for others - in excitement (euphoria). In severe cases of hypoxia, a period of euphoria is replaced by a sharp depression of the psyche. At an altitude of 5000 m or more, general diffuse inhibition develops with the transition to sleep.

In rare cases, loss of consciousness occurs.

The initial changes in the central nervous system during mountain sickness, which in elderly people can occur already at an altitude of 2000-3000 m, are explained by disturbances in braking processes. In middle-aged people, internal inhibition mainly suffers, and only to a small extent changes in the irritable process are noted.

Physiological studies have established that even when staying at an altitude of 2000-4000 m for 40-50 minutes, disorders of reflex activity on the part of the central nervous system can be determined: “shortening of the latent period, increasing the magnitude of the conditioned motor reaction, and in some cases, disinhibition of differentiation” .

At altitudes of about 6000 m, a violation of internal inhibition is determined in the direction of weakening, reducing the closure function of the cerebral cortex.

The effect of air rarefaction on higher nervous activity depends both on irritation of the chemoreceptors of blood vessels and tissues as a result of a decrease in the partial pressure of oxygen, and on the irritation of the mechanoreceptors of the gastrointestinal tract, middle ear, and accessory cavities due to the expansion of the gas contained in them.

When rising to high altitudes, the flow of impulses into the cerebral cortex can exceed the limit of the working capacity of nerve cells and lead to the development of extreme inhibition, which radiates widely throughout the cortex and extends to the subcortical nerve centers. Nervous processes become inert, phase states develop, especially ultraparadoxical and inhibitory reactions.

However, changes in the nervous system are not limited to disorders of higher nervous activity. Quite often, with mountain sickness, changes in the peripheral nervous system can be observed: decreased pain and tactile sensitivity, paresthesia of various parts of the body.

On the part of the sensory organs, one can indicate a decrease in visual acuity, narrowing of visual fields, deterioration of night vision, weakening of accommodation, and prolongation of adaptation to darkness. Hearing can decrease at relatively high altitudes (5000-6000 m).

The sense of smell and tactile sensitivity decreases. Somewhat earlier, deterioration in coordination of movements occurs, manifested in awkwardness and clumsiness, and difficulties in performing usual work. Tremors of small muscles and even paralysis are often observed.

In non-acclimatized individuals, when ascending to a height, a reactive increase in gas exchange occurs, however, as observations of people living at high altitudes show, in well-acclimatized climbers there are no significant changes in basal metabolism and thermoregulation. Only with severe mountain sickness can the temperature drop. Muscular strength of the arms at an altitude of 2400 m decreases by 25%, and at an altitude of 3400 m - by 1/3 of the original figures at sea level.

Changes in the cardiovascular system

First of all, starting from an altitude of 2000 m, disorders of the cardiovascular system are manifested by increased heart rate and increased heart contractions. These disorders, on the one hand, may be a consequence of changes in the nervous regulation of cardiac activity, and on the other hand, they are caused by hypoxia of the heart muscle itself. An increase in the amount of circulating blood is also important. A sharp increase in heart rate when rising to altitude is a sign of poor endurance to the lack of oxygen.

Climbing uphill to an altitude of 1500-2000 m is usually accompanied by a moderate increase in blood pressure, primarily systolic. At an altitude of 2500-3000 m, an increase in diastolic pressure is also observed. At high altitudes, with the development of pronounced symptoms of mountain sickness due to weakening of cardiac activity, blood pressure drops and venous pressure rises.

With a long stay at an altitude of 2000-3000 m, blood pressure tends to normalize. The influence of acclimatization on the state of vascular tone is also proven by observations of people living in mountainous areas at an altitude of 3000-4000 m above sea level. Their blood pressure is not only not increased, but, on the contrary, slightly decreased.

In the mechanism of increased blood pressure during mountain sickness, the main importance is given to the influence of hypoxia on the central nervous system, as well as on the carotid and aortic receptor zones. Of no small importance is the effect of carbon dioxide directly on the vasomotor center, increasing the amount of circulating blood and systolic volume.

With a pronounced degree of mountain sickness, hyperemia of the mucous membranes, cyanosis, thickening of the fingertips, and dilation of the veins in the periphery are observed. Due to the overflow of blood vessels, nasal, pulmonary and gastric bleeding may occur.

Data on the effect of hypoxia during mountain sickness on the heart muscle are contradictory. Observations indicating an increase in heart size have not been confirmed in studies. Considering the changes in hemodynamics that occur during hypoxia at high altitudes (increased and intensified heart contractions, increased amount of circulating blood, increased blood pressure), it should be assumed that the observed increase in heart size in acute cases may be temporary due to stretching of the cavities, and in long-term hypoxia, it is natural to expect the development of hypertrophy of the heart muscle.

Electrocardiographic changes are characterized by prolongation of the P-Q interval, a decrease, smoothing or biphasic T wave, and a decrease in the S-T interval. These electrocardiographic signs of myocardial hypoxia are often found in individuals who complain of a feeling of tightness and pressure behind the sternum.

In weakened individuals, with insufficient physical development and with certain diseases of the heart muscle, especially in old age, these changes in the cardiovascular system occur much earlier, are more pronounced and are accompanied by shortness of breath with minor physical exertion.

Changes in the external respiration system. Climbing even to a small height is always accompanied by natural changes in breathing. For different individuals, the height at which breathing disorders appear is different and its numbers vary widely.

All other things being equal, in non-acclimatized people, increased breathing occurs when rising to a height of 1000-2000 m, which approximately corresponds to a decrease in oxygen content in the blood by 5%.

Changes in the respiratory system

Minor physical exertion at altitude is accompanied by shortness of breath. Quite often, especially at high altitudes, so-called periodic breathing is observed, which is characterized by extended intervals after 3-4 normal breaths and resembles Cheyne-Stokes breathing. This kind of abnormal breathing depends on depression of the respiratory center and is a consequence of hypoxia.

Changes in the depth of breathing during oxygen starvation are more pronounced and are often the first manifestations of altitude sickness. Deep breathing and, at the same time, an increase in minute volume occur as a result of irritation of the respiratory center, the nerve cells of which are most sensitive to a lack of oxygen. Along with this, increased breathing and a simultaneous decrease in its depth are sometimes a sign of the occurrence of catarrhal phenomena in the respiratory tract and lungs.

The vital capacity of the lungs at altitude decreases not only as a result of these breathing disorders, but also due to the high position of the diaphragm when the volume of gases in the intestines expands.

In the origin of functional disorders on the part of the external respiration system, the drop in carbon dioxide tension in the alveolar air is of no small importance. The close connection and interdependence between the minute volume and tension of carbon dioxide, which exists at normal atmospheric pressure, is violated in conditions of a rarefied atmosphere. It is known that during shortness of breath caused by oxygen starvation, there is an increased leaching of carbon dioxide from the lungs and a decrease in its tension in the alveolar air. This in turn leads to a decrease in the excitability of the respiratory center, a decrease in the dissociation of oxyhemoglobin and the development of alkalosis.

In severe cases of mountain sickness, when breathing becomes frequent and shallow, oxygen deprivation progressively increases. As a result of incomplete combustion of carbohydrates, lactic acid accumulates in the blood and tissues. Further depression of the respiratory center and decreased breathing, in turn, lead to the accumulation of carbon dioxide in the blood and also contribute to the development of acidosis.

Changes in the digestive system

It is known that prolonged stay at high altitudes is often accompanied by weight loss. Weight loss can be explained not only by the effect of hypoxia on appetite, which is significantly distorted and reduced (especially for fatty foods and meat), but also by insufficient absorption of water, sodium chloride and other nutrients. A decrease in the absorption of fats, carbohydrates and proteins occurs as a result of inhibition of secretion and acid-forming function of the stomach. This also explains the intestinal dysfunction. Experiments in a pressure chamber showed that hypoxia disrupts the function of all digestive glands.

The effect of hypoxia on gastric secretion was studied in detail by Piquet and van Leer. It turned out that in experiments on animals, when the partial pressure of oxygen is reduced to 117 mm Hg (this approximately corresponds to an altitude of 2500 m), a decrease in the secretion of gastric juice is observed. The authors found the most pronounced decrease in gastric secretion at a partial pressure of oxygen equal to 94 mmHg (4000-4500 m).

Of particular interest are experiments performed on dogs with Pavlovian and Heidenhain ventricles. It turned out that hypoxia causes depression of gastric secretion much earlier in dogs operated on according to Heidenhain with transection of the nerve branches of the small ventricle. In dogs operated on according to Pavlov, the decrease in secretion at the same degree of hypoxia was less significant.

Similar differences were obtained when studying acidity. If in animals with a Pavlovian ventricle the pH of the gastric juice does not change up to an altitude of 7000-7500 m (partial pressure of oxygen 63 mm Hg), then in dogs with a Heidenhain ventricle the decrease in acidity begins already from an altitude of about 5000-5200 m.

In addition, it turned out that in dogs with a Heidenhain ventricle there is a decrease in chlorides in the gastric juice, while in dogs with preserved innervation of the small ventricle the chloride content in the gastric juice does not change.

These data undoubtedly indicate the leading role of the nervous system in the regulation of gastric secretion and, in turn, once again testify in favor of the influence of hypoxia on higher nerve centers.

Hypoxia also has a significant effect on the motility of the gastrointestinal tract. Violation of the motor function of the ventricle is characterized by spastic contractions, increased tone, and delayed emptying. With significant hypoxia at altitudes of 5000-6000 m or more, leading to severe mountain sickness, the tone of the pyloric sphincter, on the contrary, decreases.

Observations show that even with a mild degree of mountain sickness in conditions of moderate hypoxia, disturbances in the digestive system can manifest in a person with a feeling of fullness, distension in the epigastric region, nausea, vomiting, and diarrhea that cannot be treated with medication. Often these functional disorders are preceded by changes in the central nervous system.

Changes in the genitourinary system

The effect of hypoxia on urine output has not been sufficiently studied. There are indications that at altitudes starting from 4200 m, oliguria is quite often observed. The decrease in urination is associated with a vascular factor as a result of increased secretion of adrenaline.

This assumption is confirmed by observations indicating an increase in the function of the adrenal glands up to their complete depletion. With severe and prolonged hypoxia in rabbits under a pressure of 379 mm Hg (altitude 5400 m), hypertrophy was first noted, and then the development of degenerative changes in the adrenal glands.

Based on the data obtained, the authors are inclined to believe that symptoms of mountain sickness such as lethargy, fatigue, headache, nervous excitability and asthenia can be explained by insufficiency of adrenal gland function or an increased need for corticoadrenal hormones.

Changes in the blood system

Ascent to altitude is accompanied by a natural increase in the number of red blood cells in the peripheral blood. This increase is more significant the higher a person rises into the atmosphere. So, for example, at an altitude of 1500 m the number of red blood cells reaches 6,500,000, at an altitude of 4500-5000 m - 7,000,000 - 8,000,000 per 1 mm3 of blood. Along with this, an increase in hemoglobin content is observed. According to Fitzgerald's law, for every 200 m of mercury decrease in atmospheric pressure, hemoglobin increases by 10%. The color index does not change significantly.

Several theories have been proposed to explain polycythemia, which occurs in a rarefied atmosphere under conditions of decreased partial pressure of oxygen. Among them, the most substantiated are theories that explain the increase in the number of red blood cells by an increase in the mass of circulating blood as a result of contractions of the spleen, blood thickening, as well as the influence of solar radiation and, primarily, cosmic rays.

In light of the latest advances in physiology and clinical practice, decisive importance in the occurrence of polycythemia should be given to the effects of oxygen starvation on hematopoiesis. In experiments and as a result of observations in humans, it has been proven that during hypoxia, rapid regeneration of the red germ occurs in the bone marrow, and normoblasts can appear in the peripheral blood.

The stimulating effect of oxygen starvation on the bone marrow is also supported by the fact that at high altitudes, significant reticulocytosis is observed in the peripheral blood, 2-3 times higher than normal. Clarification of the specific mechanisms involved in the implementation of the pathogenic effect of hypoxia on hematopoiesis is the task of further observations. However, even now, based on research, it should be assumed that a significant role in increasing the functional activity of the bone marrow belongs to the central nervous system, which regulates the inclusion of compensatory reactions in response to hypoxia.

A natural reaction of the bone marrow when rising to altitude is an increase in the number of blood platelets. On the white blood side, moderate lymphocytosis is noted with a normal number of leukocytes. Severe hypoxia may be accompanied by moderate leukopenia.

The viscosity of blood at high altitudes increases slightly, but the same cannot be said about specific gravity. If normally it is 1056, then already at an altitude of 1800 m, due to an increase in the number of red blood cells and blood platelets, the specific gravity of blood is 1067, and at an altitude of 4000 m it is 1073. The osmotic resistance of red blood cells increases. Blood clotting time decreases.

An increase in the number of red blood cells in the peripheral blood at high altitudes is naturally accompanied by an increase in the oxygen content in the blood, but the saturation of hemoglobin with it is significantly reduced.

Changes in blood pH during hypoxia are initially characterized by alkalosis due to the leaching of carbon dioxide during hyperventilation, as well as as a result of a decrease in ammonia excretion by the kidneys. Subsequently, with an increase in oxygen starvation and disturbances in oxidative processes, in particular as a result of incomplete combustion of carbohydrates, lactic acid accumulates in the blood and acidosis develops.

Biochemical blood tests conducted in people under conditions of low barometric pressure at altitudes exceeding 4000-5000 m also indicate an increase in the content of sugar, bilirubin and cholesterol. The content of blood chlorides, as a rule, remains unchanged. With regard to calcium, there is evidence of some reduction, apparently due to increased adrenal function.

Prevention of altitude sickness

Observations of the functional state of physiological systems in residents of mountainous regions show that during a long stay at low altitudes, a number of changes occur in the human body that allow one to maintain normal life activity.

Climbers who climb mountains again, although they get tired, suffer from altitude sickness much less than those who climb for the first time.

The greatest importance in acclimatization to the action of rarefied air in mountainous areas is an increase in the volume of pulmonary ventilation, hypertrophy of the heart muscle, dilatation of the pulmonary capillaries and alveoli, an increase in the number of red blood cells and hemoglobin content, a change in the oxygen capacity of the blood and the form of dissociation, and an increase in blood alkalinity. An important role in this, undoubtedly, is played by the central nervous system and those compensatory metabolic mechanisms that increase the resistance of body tissues to oxygen starvation.

It is quite obvious that for each person at a certain altitude above sea level, adaptation to oxygen starvation will require a different time. Acclimatization occurs faster in young (from 24 to 40 years old) physically healthy people. After only 8-10 days of staying at an altitude of 2000-3000 m, as a result of the action of compensatory mechanisms, the number of red blood cells and hemoglobin increases, the activity of the cardiovascular system and external respiration, as well as other physiological functions, increases.

The most important measure for the prevention of mountain sickness in people participating in climbing to high altitudes is strengthening their physical condition.

According to the existing instructions for climbers, in order to prevent altitude sickness, it is recommended to carry out two months of acclimatization by successive ascents with two breaks for descending to an altitude of 2000 m, as well as staying in a training camp at an altitude of 5000 m for 1.5 months.

However, as physiological studies have shown, the acclimatization period can be significantly shortened if you first systematically engage in sports throughout the year.

According to the observations of the authors who took part in the high-altitude expedition, year-round training can significantly increase the body's adaptive abilities to oxygen starvation. Even at an altitude of 7050 m for 14 days, climbers who did not use oxygen-breathing equipment remained in good health. Compensatory reactions from internal organs, manifested by increased heart rate, changes in blood pressure, and increased respiratory rate, were weakly expressed and unstable.

Essential for good tolerance of low partial pressure of oxygen in a rarefied atmosphere, along with pre-training, is the correct organization of nutrition and water-salt regime. In particular, taking a large amount of fluid (about 3 liters per day) has a beneficial effect, which is apparently associated with the acceleration of the excretion of more under-oxidized metabolic products by the kidneys.

Another method of preventing mountain sickness is systematic training in a pressure chamber before climbing using a special technique. Thus, a systematic climb of 2500 m in combination with five climbs to a height of 3000 to 4500 m increases the “ceiling” of endurance when climbing mountains.

An important means of preventing mountain sickness is regular inhalation of oxygen-depleted gas mixtures, as well as ultraviolet irradiation, before climbing.

Carrying out a set of preventive measures for acclimatization helps to increase endurance.

Mountain sickness in acclimatized people can develop at significantly higher altitudes than in non-acclimatized people, even starting from 5500-6000 m with significant physical stress.

Chronic mountain sickness

In cases where acclimatization does not occur and the climber remains at the same altitude, subacute mountain sickness can become chronic.

There are two forms of chronic mountain sickness: emphysematous and erythraemic. The symptoms of chronic mountain sickness are the same as in the subacute form, but they are more pronounced: severe cyanosis up to a crimson color, hyperemia of the sclera and swelling of the eyelids, thickening of the fingertips, nosebleeds, and hemoptysis. Quite often aphonia, dry skin, and paresthesia occur.

Along with signs of heart failure, pronounced changes in the psyche are observed, up to nervous exhaustion and a complete change in personality. Polycythemia and leukocytosis increase. Protein appears in the urine.

In the chronic form of mountain sickness, the utilization of oxygen by tissues is sharply impaired as a result of a decrease in oxygen saturation in arterial blood to 75%. The increase in the arteriovenous difference in oxygen consumption when descending to sea level cannot but indicate the participation in the genesis of mountain sickness not only of hypoxemic, but also histotoxic hypoxia.

Treatment of altitude sickness

The difficulties of climbing high mountain peaks in small groups require that climbers be familiar with the rules of self- and mutual aid. Each participant in a high-altitude expedition must clearly imagine the danger associated with the development of oxygen starvation, know the main symptoms of altitude sickness and take appropriate measures in a timely manner.

In cases where a large group of climbers is involved in climbing to a significant height, it is advisable to include a doctor in the expedition. Special medical care must also be provided for long-term work, even at low altitudes (2000-3000 m).

It is quite obvious that the organization and volume of therapeutic assistance for mountain sickness in each specific case will be determined not only by the severity of symptoms, but also by the conditions in which this assistance can be provided.

When the initial symptoms of mountain sickness develop, when headache, shortness of breath, palpitations, and fatigue occur in the midst of complete well-being, it is necessary to stop climbing. The sick person should be warmed up and given hot tea.

As mild stimulants of the central nervous system, caffeine with bromine, ginseng tincture) 15 drops per dose, Cola in tablets of 0.5 g or in solution (Extr. Colae fluidi) no 15 drops 2 times a day are indicated, as well as Chinese schisandra in powder, 0.5 g per dose (Pulv. Schizandrae chinensis). It should be taken into account that the use of Chinese Schisandra is contraindicated in cases of increased blood pressure, nervous agitation and severe cardiac dysfunction.

In the presence of persistent tachycardia, it is advisable to prescribe drugs that reduce and increase heart contractions. In mountainous conditions, tincture of lily of the valley or adonizide, 15 drops per dose, 2 times a day, can be used for this purpose.

Since enormous physical activity over a long period of time significantly increases the need for vitamins, when signs of mountain sickness appear, it is quite reasonable to prescribe them in therapeutic doses. Vitamins B1, B2, B6, C and A are especially indicated, which are part of the enzymes involved in the regulation of redox processes and are closely related to the metabolism of carbohydrates, proteins and fats.

It is advisable to use a multivitamin complex.

If, as a result of these measures, the patient’s condition does not improve, it is necessary to descend to a safe altitude (2000-2500 m). A special place in easing the tolerance of the difficulties of climbing and in eliminating the initial manifestations of mountain sickness is occupied by rational nutrition and a water-drinking regime.

Until recently, it was believed that climbers needed to limit their fluid intake to prevent heart failure. However, observations have shown that the tolerance of climbing is significantly easier if the daily regimen includes at least 3 liters of fluid. You should drink slowly and in small portions.

During high-altitude ascent, the following drinking regime is recommended. During breakfast before leaving the camp - complete satisfaction of the need for liquid (tea, coffee). When climbing - drink sweet acidified water in the amount of 0.75-1 liters in fractional portions. During an overnight stop, the need for fluid is again fully satisfied. Drinking hot tea, eating predominantly carbohydrate foods, and taking glucose tablets are especially recommended. Meat and fatty foods are better tolerated when hot. The daily caloric intake of climbers should not be less than 5000 large calories.

With the development of severe symptoms of mountain sickness, when severe weakness, chilliness, painful headache, significant shortness of breath, tachycardia, cyanosis and other signs appear without noticeable previous deterioration of the condition, the best treatment is to descend the victim to a safe altitude or give oxygen.

The best oxygen concentration for breathing is 40-60%.

If for some reason descent is not possible for a long time and there is no oxygen-breathing equipment, then, in addition to the medications listed above, stronger heart medications are indicated in the form of corazol in tablets of 0.1 or cordiamine, 20 drops per dose.

If there is a doctor in the group climbing a mountain peak, it is good to use cardiac remedies as follows: 1 ml of cordiamin, 2 ml of camphor oil mixed with 1 ml of caffeine, it is better to inject it under the skin; in case of phenomena of sharply increasing weakness of cardiac activity - a solution of strophanthin 1:1000 or 0.06% korglykon 0.3-0.5 ml per 20 ml of 40% glucose is administered intravenously, and in case of respiratory depression - 1 ml of a solution of cititon or 1 ml 1 % lobeline - intramuscularly or intravenously.

Along with this, it is necessary to help reduce the need for oxygen by creating conditions for peace, eliminating not only physical, but also mental stress and anxiety. Since the central nervous system suffers first of all during mountain sickness, where necessary and possible, the use of sleeping pills is indicated in order to create extreme inhibition. Extreme inhibition significantly increases the body's adaptability to hypoxia. Sleeping pills protect brain cells from exhaustion and bring metabolism into line with the limited supply of oxygen.

The quality of treatment in the event of mountain sickness will ultimately be determined not so much by the choice of medications, but by the degree of preparedness of the expedition (including acclimatization), the ability to identify the earliest signs of oxygen deprivation and the search for all opportunities to provide the most effective assistance to the victim in this particular situation.

Mountain sickness (miner, acclimukha - slang) is a painful condition of the human body that has risen to a significant altitude above sea level, which occurs as a result of hypoxia (insufficient oxygen supply to tissues), hypocapnia (lack of carbon dioxide in tissues) and is manifested by significant changes in all organs and systems of the human body.

How does mountain sickness develop?
A standard misconception is that mountain fever is caused by a lack of oxygen in the blood caused by a lack of it in the atmosphere. But science is not asleep, this issue has been studied and, it turns out, not everything is so simple: the saturation of the air with oxygen has nothing to do with it. The sensations of the human body are influenced by several factors.

Absolute air humidity decreases with altitude. Above the sea the humidity is close to 100%, at 3000 meters it is only 26%, and at 6000 meters the “great dryness” is 5%. Of course, rain and snow periodically saturate the atmosphere with water, but not for long.

Atmospheric pressure decreases: every 11 meters of rise it drops by about 1 mmHg. The concentration of oxygen in the atmosphere, contrary to popular belief, remains almost unchanged. But the partial pressure, that is, the pressure of an individual component of a gas mixture, where the total pressure of the gas mixture is the sum of the partial pressures of its components (it’s difficult to imagine, but the pattern is clear) - changes greatly (the plate is taken from the article by S. B. Tikhvinsky).

That is, oxygen at altitude is simply less absorbed by the body. On a beach near a warm sea, blood is able to absorb 96-98% of oxygen. And at an altitude of 2 km - only 92%, at an altitude of 4 km (Kinabalu) - 85%, at 5.5 km (Elbrus) - 80%, at the altitude of Everest (8848 meters) - 60%. However, venous blood has the same oxygen content everywhere. It is this difference in the income and expenditure of the precious gas of life that leads to hypoxia - an insufficient supply of oxygen to the body’s tissues.

At what altitudes do symptoms of “mountain sickness” begin?

This greatly depends on air humidity. And not on geographic latitude and distance from the equator (a popular prejudice, by the way). If in the Alps, where humidity is high, discomfort begins at 2500 meters, in the Caucasus - at 3000, then in the Tien Shan, Pamirs and Andes (average humidity) hypoxia occurs at an altitude of 3500-4500 thousand meters. And in the Himalayas or in arid Tanzania - on Kilimanjaro - "miner" syndromes are observed above 5000 meters. Otherwise, continuous crowds of curious tourists would not wander to the foot of Everest every year.

In the mountains, especially high ones, other factors are added to the decrease in oxygen in the blood: physical fatigue, hypothermia, and dehydration at altitude. And in case of accidents there are also injuries. And if in such a situation you do not influence the body correctly, physiological processes will take place in a “vicious circle”, complications will arise, and the life of the climber may be in danger. At altitude, the speed of pathological processes is very high; for example, the development of pulmonary or cerebral edema can cause the death of the victim within a few hours.
The main difficulty in diagnosing mountain sickness is primarily due to the fact that most of its symptoms, with a few exceptions (for example, periodic intermittent breathing), are also found in other diseases: cough, difficulty breathing and shortness of breath - in acute pneumonia, abdominal pain and digestive disorders - in case of poisoning, disturbances of consciousness and orientation - in case of traumatic brain injury. But in the case of mountain sickness, all of these symptoms are observed in the victim either during a rapid rise to altitude, or during prolonged stay at altitude (for example, when waiting out bad weather).

Many conquerors of eight-thousanders noted drowsiness, lethargy, poor sleep with symptoms of suffocation, and their health immediately improved with a rapid loss of altitude.
Common colds, dehydration, insomnia, overwork, and drinking alcohol or coffee also contribute to the development of altitude sickness and worsen well-being at altitude.

And simply the tolerance to high altitudes is very individual: some athletes begin to feel a deterioration in their condition at 3000-4000 m, others feel great at a much higher altitude.

That is, the development of mountain sickness depends on individual resistance to hypoxia, in particular on:
- gender (women tolerate hypoxia better),
- age (the younger the person, the worse he tolerates hypoxia),
- general physical fitness and mental state,
- speed of rise to height,
- as well as from past “high-altitude” experience.

The combination of the above factors leads to the fact that the altitude of development of mountain sickness for different people and different conditions can be quite variable. Some begin to suffer from oxygen deficiency already at an altitude of 2000 m, while others do not feel its effect even at 4000 m.
Most healthy, non-acclimatized inhabitants of the plains begin to feel the effects of altitude in the region of 2500-3000 m, and with intense physical work, even at lower altitudes. At an altitude of about 4000 m, even absolutely healthy people experience slight malaise, and acute mountain sickness is registered in 15-20% of climbers. At an altitude of 6500-7000 m, complete acclimatization is apparently impossible at all, and therefore participants in expeditions to eight-thousanders around the world note numerous functional disorders and progressive signs of mountain sickness. In high-altitude mountaineering there is a term “lethal zone” or “death zone”.

Altitude sickness clinic
The acute form of mountain sickness occurs when non-acclimatized people move quickly (within several hours) to high altitudes, usually to an altitude of more than 3500 m. Its clinical symptoms develop rapidly. In the subacute form of mountain sickness, they do not develop as quickly and last longer (up to 10 days).
There are mild, moderate and severe degrees of mountain sickness.
Mild mountain sickness is characterized by the appearance of lethargy, malaise, rapid heartbeat, shortness of breath and dizziness in the first 6-10 hours after ascending to altitude. It is also characteristic that drowsiness and poor sleep are observed simultaneously. If the rise to altitude does not continue, these symptoms disappear after a couple of days as a result of the body’s adaptation to the altitude (acclimatization). There are no objective signs of a mild form of mountain sickness. If these symptoms appear within 3 days after rising to altitude, the presence of some other disease should be assumed.

Moderate mountain sickness is characterized by inadequacy and a state of euphoria, which are subsequently replaced by loss of strength and apathy. Symptoms of hypoxia are already more pronounced: severe headache, dizziness. Sleep is disturbed: patients have trouble falling asleep and often wake up from suffocation, they are often tormented by nightmares. With exertion, the pulse increases sharply and shortness of breath appears. As a rule, appetite completely disappears, nausea appears, and sometimes vomiting. In the mental sphere - there is inhibition on the route, poor or slow execution of commands, and sometimes euphoria develops.
With a rapid loss of altitude, your health immediately improves before your eyes.

In severe cases of mountain sickness, the symptoms of hypoxia affect all organs and systems of the body. The result is poor physical well-being, rapid fatigue, heaviness throughout the body, which prevents the athlete from moving forward.
In the absence of treatment and descent, mountain sickness leads to serious complications - pulmonary and cerebral edema.

Prevention of altitude sickness

Climbers and mountain tourists planning climbs and hikes in the mountains should understand that the likelihood of mountain sickness in participants is reduced by:

Good informational and psychological preparation,
- good physical fitness,
- high-quality equipment,
- correct acclimatization and well-thought-out climbing tactics.

This is especially important for high altitudes (over 5000 m)!

Prevention of mountain sickness consists, first of all, in the advance creation of a good sports form of the athlete during the preparation phase for events in the mountains. With good general physical fitness, the athlete is less tired, better able to withstand the effects of cold, all his organs are prepared for high loads, including in the presence of oxygen deficiency. In particular, for athletes planning to climb high altitudes, it is necessary to include anaerobic training in the training cycle (running uphill, running with breath holding).
When climbing at high altitudes, it is necessary to take multivitamins (preferably with a complex of microelements), antioxidants: tinctures of ginseng, golden root, Rhodiola rosea, ascorbic acid, riboxin (it is advisable to carry out additional fortification of the body in advance, 1-2 weeks before leaving for the mountains ).
Directly in the mountains, it is important to have good and properly carried out acclimatization, moderate alternation of ascents to heights and descents to the overnight location with constant monitoring of the well-being of group members. In this case, you should gradually increase both the height of the base camp and the height of the “peak” ascent points.
You can encounter a situation where an “athlete”, tired of the office, finally escapes into nature - to the mountains, in this case - and decides to relax and “to sleep better” take a dose of alcohol.
So here it is:
The tragic consequences of such “relaxation” in history, even not so long ago, are known: this does not contribute to acclimatization at all, but on the contrary.

Alcohol, even in small doses, is strictly contraindicated in conditions of hypoxia, as it depresses respiration, impairs interstitial fluid exchange, increases the load on the heart and increases oxygen starvation of brain cells.

Mountain sickness (the medical term for altitude hypoxia) is often caused by a lack of oxygen in the air at high altitudes and is a type of altitude sickness.

Anyone can suffer from altitude sickness. Its symptoms begin to appear in different people at different altitudes above sea level. Most often, climbers, skiers and tourists in high mountain areas suffer from high-altitude hypoxia. Factors contributing to altitude sickness are, first of all, the physical condition and preparation of the person, as well as the speed of ascent to a particular altitude. Mountain sickness usually occurs at an altitude of two to three thousand meters above sea level. However, some people experience problems with well-being even at one and a half thousand meters.

Primary symptoms of mountain sickness

High-altitude hypoxia usually appears within a few hours after reaching a certain point above sea level. Symptoms of altitude sickness may include:

• headache,
• irritability,
• dizziness,
• muscle pain,
• fatigue or insomnia,
• loss of appetite,
• nausea or vomiting
• swelling of the face, arms and legs.

A more serious condition may cause swelling of the brain and lead to hallucinations, confusion, difficulty moving (walking), severe headaches, and extreme fatigue. Severe mountain sickness also causes fluid to accumulate in the lungs, leading to shortness of breath even while resting. Severe mountain sickness is a direct threat to life, and if symptoms occur, you should immediately seek medical help.

How to treat mountain sickness

Diagnosis and treatment of mild altitude hypoxia are usually not required as symptoms usually resolve within a day or two. Doctors sometimes recommend that people with altitude sickness take aspirin or ibuprofen to relieve muscle pain. Climbers take medications that prevent or treat many of the symptoms of high-altitude hypoxia.

Severe mountain sickness is a serious and life-threatening health condition that must be treated in hospital with oxygen therapy and procedures to reduce swelling in the brain and the amount of fluid in the lungs. People with severe symptoms should be moved to a lower altitude.

Is it possible to prevent altitude sickness?

The easiest way to avoid the initial symptoms of altitude sickness is to slowly ascend to a higher altitude, which allows the body to become accustomed to the lower oxygen content in the air. At high altitudes, while the body gets used to the high altitude, it is important to avoid stress for the first few days and limit physical activity.

What are the causes of altitude sickness

The percentage of oxygen in the air, 21, remains virtually unchanged up to 21,000 meters. The RMS velocities of diatomic nitrogen and oxygen are very similar, and therefore there is no change in the ratio of oxygen to nitrogen. However, air density (the number of molecules of both oxygen and nitrogen per given volume) falls with increasing altitude, and the amount of oxygen available to support mental and physical activity decreases above 3,000 meters. Although modern passenger airliners fly at altitudes less than 2,400 meters, some passengers on long-haul flights may experience some symptoms of altitude sickness.

Other causes of altitude sickness

The rate of ascent, the altitude reached, the amount of physical activity at high altitude, and individual susceptibility are the main factors contributing to the occurrence of high-altitude hypoxia and its severity. Dehydration at high altitudes can also contribute to symptoms of altitude sickness.

Altitude hypoxia usually occurs after rapid ascent and can usually be prevented by slow ascent. In most cases, symptoms are temporary and decrease with acclimatization. However, in extreme cases, altitude sickness can be a fatal condition.

People's sensitivity to heights

People have varying susceptibility to altitude sickness. In some healthy people, acute mountain sickness can occur at an altitude of about 2000 meters above sea level, for example, at ski resorts. Symptoms often appear 6-10 hours after rising and usually go away within one to two days, but sometimes develop into more serious conditions. Symptoms of high altitude hypoxia include headache, fatigue, stomach problems, dizziness and sleep disturbances. Physical activity increases the main symptoms.

Main symptoms of mountain sickness

Headache is the main symptom used to diagnose altitude sickness. Headache occurring at altitudes above 2400 meters in combination with any one or more of the following symptoms may indicate the presence of altitude sickness:

Severe symptoms of altitude sickness

Symptoms that may indicate a life-threatening condition include:

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Life-threatening symptoms of altitude sickness

The most serious symptoms of altitude sickness occur due to edema (fluid accumulation in tissues). At very high altitudes, people can develop either high-altitude pulmonary edema or high-altitude cerebral edema. The physiological cause of edema caused by altitude has not been definitively established. Drugs such as dexamethasone can help temporarily relieve symptoms so you can get down the mountain on your own.

High altitude pulmonary edema

High-altitude pulmonary edema can progress rapidly and is often fatal. Symptoms include fatigue, severe shortness of breath at rest, and a cough that is initially dry but may progress to pink, frothy sputum. Descending to lower altitudes alleviates the symptoms listed above.

High altitude cerebral edema

Cerebral edema is a life-threatening condition that can lead to coma or death. Symptoms include headache, fatigue, blurred vision, bladder dysfunction, bowel dysfunction, loss of coordination, paralysis on one side of the body and confusion. Descending to lower altitudes can save the life of a person with cerebral edema.

How to avoid altitude sickness

Slow ascent is the best way to avoid altitude sickness. You should also avoid strenuous physical activities such as skiing, mountain hiking, etc. Since alcohol tends to cause dehydration, which worsens high-altitude hypoxia, the best option is to avoid drinking alcohol completely during the first 24 hours in the mountains.

Altitude acclimatization

Altitude acclimatization is the process of the body adapting to the decrease in oxygen in the air at higher levels to avoid altitude sickness. For climbers, a typical acclimatization regimen might be to stay at base camp for a few days, climb up to a higher camp (slowly), and then return to base camp. The subsequent ascent includes an overnight stay. This process is repeated several times, each time with more time spent at higher altitudes to allow the body to adjust to oxygen levels. Once the climber has acclimated to a given altitude, the process is repeated at higher levels. The main rule is not to climb more than 300 meters a day before going to bed. That is, in one day you can climb from 3000 to 4500 meters, but then you should go back down to 3300 meters for the night. Special high-altitude equipment that produces hypoxic (oxygen-depleted) air can be used for high-altitude acclimatization, reducing its time.

Drug treatment for mountain sickness

Some medications can help you quickly climb to altitudes above 2,700 meters. However, experts, particularly those at the Everest Base Camp Medical Center, caution against their routine use as a substitute for the sensible acclimatization schedule described above, except in certain cases where a rapid ascent is necessary or due to terrain conditions.

Randomized controlled trials highlight that some medications that may help prevent altitude sickness, despite their popularity, are not always effective in preventing altitude hypoxia, and, for example, phosphodiesterase inhibitors may even worsen altitude sickness headaches.

Oxygen enrichment

In high altitude environments, oxygen enrichment can counteract altitude-associated hypoxia. At an altitude of 3,400 meters, increasing the oxygen concentration by 5 percent through an oxygen concentrator and the existing ventilation system effectively simulates an altitude of 3,000 meters.

Other methods to combat altitude sickness

Increasing your water intake can also help with acclimatization by replacing fluid lost from heavy breathing with dry air at altitude, but excessive amounts are not beneficial and can cause dangerous hyponatremia.

Oxygen from gas cylinders or liquid containers is delivered directly through a nasal cannula or mask. Oxygen concentrators based on pressure adsorption can be used to generate oxygen if electricity is available. Stationary oxygen concentrators typically use PSA technology, which suffers from degradation at lower barometric pressures at higher altitudes. One way to compensate for performance degradation is to use a hub with higher bandwidth. There are also portable oxygen concentrators that can be used on vehicle DC power or internal batteries. The use of high purity oxygen by one of these methods increases the partial pressure of oxygen by increasing FiO 2 .

In addition, the use of nitric oxide helps relieve symptoms of altitude sickness.

What to do if you have obvious symptoms of altitude sickness

The only reliable treatment, and in many cases the only option available, is descent. Attempts to treat or stabilize a casualty in place at altitude are dangerous unless they are closely supervised and carried out under appropriate medical conditions. However, the following treatments may be used if location and circumstances permit:

Denial of responsibility: The information presented in this article about altitude sickness is intended to inform the reader only. It is not intended to be a substitute for advice from a healthcare professional.